x86/ima: use correct identifier for SetupMode variable

The IMA arch code attempts to inspect the "SetupMode" EFI variable
by populating a variable called efi_SetupMode_name with the string
"SecureBoot" and passing that to the EFI GetVariable service, which
obviously does not yield the expected result.

Given that the string is only referenced a single time, let's get
rid of the intermediate variable, and pass the correct string as
an immediate argument. While at it, do the same for "SecureBoot".

Fixes: 399574c6 ("x86/ima: retry detecting secure boot mode")
Fixes: 980ef4d2 ("x86/ima: check EFI SetupMode too")
Cc: Matthew Garrett <mjg59@google.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Cc: stable@vger.kernel.org # v5.3
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

arch/x86/kernel/ima_arch.c

@@ -10,8 +10,6 @@ extern struct boot_params boot_params;
 
 static enum efi_secureboot_mode get_sb_mode(void)
 {
-	efi_char16_t efi_SecureBoot_name[] = L"SecureBoot";
-	efi_char16_t efi_SetupMode_name[] = L"SecureBoot";
 	efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
 	efi_status_t status;
 	unsigned long size;
@@ -25,7 +23,7 @@ static enum efi_secureboot_mode get_sb_mode(void)
 	}
 
 	/* Get variable contents into buffer */
-	status = efi.get_variable(efi_SecureBoot_name, &efi_variable_guid,
+	status = efi.get_variable(L"SecureBoot", &efi_variable_guid,
 				  NULL, &size, &secboot);
 	if (status == EFI_NOT_FOUND) {
 		pr_info("ima: secureboot mode disabled\n");
@@ -38,7 +36,7 @@ static enum efi_secureboot_mode get_sb_mode(void)
 	}
 
 	size = sizeof(setupmode);
-	status = efi.get_variable(efi_SetupMode_name, &efi_variable_guid,
+	status = efi.get_variable(L"SetupMode", &efi_variable_guid,
 				  NULL, &size, &setupmode);
 
 	if (status != EFI_SUCCESS)	/* ignore unknown SetupMode */